This invention relates to door locks, and has particular reference to a door lock of the type that is mountable in a notch in one edge portion of a door and is key-operable from at least one side to extend and retract a slidable bolt.
The invention is particularly well suited for use in a high-security lock of the type shown in U.S. Pat. No. 3,702,549, in which two escutcheon plates form the sides of the lock housing and are joined together and clamped against the sides of the door by camming devices between the plates. These devices are operable from the edge of the door when the door is open, and a finish edge plate then in installed to close the lock at the door edge.
The lock of the aforesaid patent and the lock of the present invention are designed for optimum strength, security, and effectiveness of operation, rather than for highly price-competitive situations. At the same time, compactness in construction, and smooth, trouble-free performance are important considerations, along with design features that protect the lock from tampering that might make unauthorized entry possible.
In general, at least one mortise cylinder having a key-actuated plug therein is mounted on one of the escutcheon plates, and drives a bolt-operating mechanism inside the lock to extend and retract the bolt upon turning of the key. In the lock of the aforesaid patent, the key plug carries an arm that is pivotally connected by a link to the bolt, to push and pull the bolt as the plug is turned and the arm on the key plug swings toward and away from the bolt.
The primary objective of the present invention is to improve upon the bolt-operating mechanism of the patent while retaining the advantages of that mechanism, to provide a rugger, smooth-operating and highly tamper-resistant lock that has a substantially greater bolt-throw and improved keying motions.